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Canadian officials checking reports of salmon disease in B.C.

Posted Nov. 16, 2011

Agriculture authorities are investigating a report that infectious salmon anemia was detected in two fish from an inlet in central British Columbia.

Information from Simon Fraser University indicates the disease was detected in wild sockeye salmon smolts that were collected during a study on sockeye salmon population collapse in the Rivers Inlet. The Canadian Food Inspection Agency reported Oct. 21 that federal officials were investigating the reports along with the Atlantic Veterinary College, which conducted the tests cited by the SFU announcement, and the National Aquatic Animal Health Laboratory in New Brunswick.

The internationally reportable disease has devastated salmon populations in a variety of locations, including the northeastern U.S., eastern Canada, Chile, Norway, and Scotland. It has previously not been confirmed in the Pacific Northwest, where farmed Atlantic salmon could be susceptible to the disease.

Dr. Gary D. Marty, a veterinarian and fish pathologist with British Columbia's Ministry of Agriculture, said the initial reports indicate PCR assays for infectious salmon anemia virus nucleic acid were positive for two of 48 sockeye salmon smolts tested, but none of the fish had signs consistent with the disease. He said the PCR assays are sensitive, but that confirmatory tests would be needed to determine whether sample contamination could have produced false-positive results. He said the World Organisation for Animal Health (OIE) requires additional confirmation through laboratory isolation and growth of the virus, or clear evidence of clinical disease among the sources of positive samples.

Dr. Marty said the Fish Health Auditing and Surveillance Program operated by the ministry from 2003-2010 examined dead fish on salmon farms for evidence of several diseases including ISA. Of more than 4,700 fish tested with a highly specific and sensitive PCR assay, all were negative for the virus, he said.